MAGNETIC BEARING AND COMPRESSOR USING THE SAME

摘要

PROBLEM TO BE SOLVED: To reduce electric power consumed in an electromagnet coil while maintaining linearity of control current and composite electromagnetic force in a magnetic bearing.

SOLUTION: There is provided a stator (21) with a plurality of electromagnets (24) to impart the composite electromagnetic force (F) generated by the plurality of electromagnets (24) to a drive shaft (13) whose load (Ld) varies. Then, there is provided a control unit (30) for controlling a current difference between a first coil current (IU) (an upper coil current) allowed to flow through a coil (23) of the electromagnets (24) for generating electromagnetic force whose direction is opposite to that of the load (Ld) and a second coil current (IL) (a lower coil current) allowed to flow through a coil (23) of the electromagnets (24) for generating electromagnetic force whose direction is the same as that of the load (Ld) and further controlling a position of the drive shaft (13). The control unit (30) successively regulates the second coil current (IL) so as to decrease an average value of the second coil current (IL).

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